Re: [PATCH] read-cache: make the index write buffer size 128K

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On Wed, Feb 24, 2021 at 11:36 PM Neeraj Singh <nksingh85@xxxxxxxxx> wrote:
> From a quick perusal of freebsd, st_blksize seems to be the system
> PAGE_SIZE by default (4k most of the time, I assume). The Windows
> equivalent of this value is really tuned to what you want to send down
> when bypassing the cache (to avoid partial cluster/stripe writes).

It's page-size for pipes, sockets, etc., but for real files, it's based on
a report from the underlying file system.  It's actually 8k on a typical
ancient UFS file system, 64K on UFS2, and 128K on ZFS, on FreeBSD.


> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html
> doesn't elicit much confidence. The units of st_blksize aren't even
> defined.

Despite POSIX's rather obstreperous definition of st_blksize, the
units are actually just bytes, in practice.

Chris



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